Conventional perpendicular magnetic recording (PMR) heads can be fabricated in a number of ways. FIG. 1 is a flow chart depicting a conventional method 10 for fabricating a PMR transducer using a conventional process. For simplicity, some steps are omitted. FIGS. 2-5 are diagrams a depicting conventional PMR transducer 50 as viewed from the air-bearing surface (ABS) during fabrication. The conventional PMR transducer 50 may be part of a coupled with a slider to form a PMR head. In addition, a read transducer (not shown) may be included to form a merged PMR head. For simplicity, only a portion of the conventional PMR transducer 50 is shown. The conventional method 10 is described in the context of the conventional PMR transducer 50.
An intermediate layer, chemical mechanical planarization (CMP) stop layer and hard mask layer are provided, via step 12. The intermediate layer is typically aluminum oxide. The CMP stop layer may include Ru, while the hard mask layer may include NiCr. A photoresist mask is provided on the hard mask layer, via step 16. FIG. 2 depicts the conventional PMR transducer 50 after step 14 is completed. Thus, an underlayer 52, aluminum oxide layer 54, CMP stop layer 56, and hard mask layer 58 are shown. The underlayer 52 is typically made of NiCr. Also depicted are the photoresist mask 60 and aperture 62 within the photoresist mask. The aperture 62 is located above the desired position of the PMR pole.
An aperture is formed in the hard mask layer 58 using a conventional ion milling process, via step 16. Step 16 also includes forming an aperture in the CMP stop layer 56. FIG. 3 depicts the conventional PMR transducer 50 after step 16 has been completed. Thus, a hard mask 58′ has been formed by the hard mask layer. An aperture 64 has been formed in the hard mask 58′ and the CMP stop layer 56′.
Using the hard mask 58′ and photoresist mask 60, a trench is formed in the aluminum oxide layer 54, via step 18. Step 18 is typically performed using an alumina reactive ion etch (RIE). FIG. 4 depicts the conventional PMR transducer 50 after step 18 is performed. Thus, a trench 66 has been formed in the aluminum oxide layer 54′. The top of the trench 66 is wider than the trench bottom. In addition, the trench 66 extends through the aluminum oxide layer 54′. As a result, the PMR pole (not shown) formed therein will have its top surface wider than its bottom. Consequently, the sidewalls of the PMR pole will have a reverse angle.
The conventional PMR pole materials are deposited, via step 20. A chemical mechanical planarization (CMP) is then performed, via step 22. FIG. 5 depicts the conventional PMR transducer 50 after step 22 has been performed. Thus, the conventional PMR pole 28 has been formed.
FIG. 6 is a flow chart depicting another conventional method 70 for fabricating a PMR transducer using a conventional process. For simplicity, some steps are omitted. FIGS. 7-8 are diagrams a depicting conventional PMR transducer 50′ as viewed from the air-bearing surface (ABS) during fabrication. The conventional PMR transducer 50′ may be part of a coupled with a slider to form a PMR head. In addition, a read transducer (not shown) may be included to form a merged PMR head. For simplicity, only a portion of the conventional PMR transducer 50 is shown. The conventional method 70 is described in the context of the conventional PMR transducer 50′.
PMR pole and CMP stop layers are provided, via step 72. The PMR pole layer(s) may include seed layers as well as magnetic layer(s). The CMP stop layer may include materials such as Ru or DLC. A hard mask is provided on the layers, via step 74. The hard mask covers the portion of the PMR pole layer from which the PMR pole is desired to be formed. The PMR pole is defined, typically using an ion mill and pole trim, via step 76. FIG. 7 depicts the PMR transducer 50′ after step 76 has been performed. Thus, the conventional PMR pole 68′ is shown on the underlayer 52′. The CMP stop layer 56″ and hard mask 58″ are also shown. Because of the presence of the hard mask, the top of the PMR pole 68′ is wider than its bottom.
An intermediate layer is provided on the PMR pole 68′, via step 78. A CMP is performed via step 80. FIG. 8 depicts the PMR transducer 50′ after step 80 is performed. Thus, the aluminum oxide layer 54″ is shown. Because a CMP has been performed, the top surface of the aluminum oxide layer 54″ is substantially flat and co-planar with the top surface of the CMP stop layer 56″. Fabrication of the conventional PMR transducer 50′ may be completed, via step 82. For example, step 82 may include forming a write gap (not shown) and a top shield (not shown).
Although the conventional methods 10 and 70 may provide the conventional PMR transducer 50 and 50′, there may be drawbacks. In particular, the conventional PMR poles 68 and 68′ of the conventional PMR transducers 50 and 50′, respectively, may be subject to nonuniformities. As can be seen in FIG. 3-5, the aperture 64 in the hard mask 58′ and CMP stop layer 56′ is not symmetric. In addition, fencing (not shown) from redeposition of the NiCr hard mask 58′ during step 16 of the method 10 may exacerbate asymmetries in the hard mask 58′. Consequently, the trench 66 in the aluminum oxide layer 54′ and the sidewalls of the conventional PMR pole 68 are not symmetric. Further, the CMP performed in step 22 may remove varying amounts of the aluminum oxide layer 54′. Thus, the critical dimension of the conventional PMR pole 68 in the track width direction may vary. Such variations may significantly affect the performance of the conventional PMR transducer 50. In addition, variations in the CMP of steps 22 or 80 may result in variations of the top surface of the conventional PMR transducer 50 or 50′, respectively. Further, because of the definition of the PMR pole in step 76, the shape of the conventional PMR pole 68′ may be poorly controlled. Thus, the PMR pole 68′ may be subject to variations. Thus, performance of the conventional PMR transducers 50 and 50′ may be adversely affected.
Accordingly, what is needed is an improved method for fabricating a PMR transducer.